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What is Matter?

  1. Sep 14, 2007 #1
    Is there a scientifically accepted definition of matter, and if so, what is it?
  2. jcsd
  3. Sep 14, 2007 #2
    What is matter?

    'It is the real substance of which actual physical objects - the 'things' of this world - are composed.' Sir Roger Penrose.
  4. Sep 14, 2007 #3
    Thanks, but hardly scientific.
  5. Sep 14, 2007 #4
    How much more scientific could you get?
  6. Sep 14, 2007 #5
    Okay? - Is there anything wrong with this description of matter? . . .

    Matter has mass and occupies space. Matter occupies it’s own space and cannot occupy the space of other matter. An atom is the smallest indivisible unit of matter. Anything subatomic is not matter.
  7. Sep 14, 2007 #6
    Newton would've probably agreed with your mass statement. Yet Einstein says E=mc2. In other words, energy and mass are interchangeable. This is commonly appreciated when considering particles, people appreciate the interchangeability when decaying Uranium atom seems to swap mass for energy. But it seems to me less appreciated that Maxwell's electromagnetic field (which carries energy, right?) must therefore carry mass, thus a field is also matter. In fact a substantial portion of a body's mass is derived from the elecromagnetic fields within it! Of course, Einstein's gravitational field would therefore be matter too, but it is difficult to pin down because of reference frame considerations (don't ask me!), thing get more messy in the quantum world, but I won't even attempt to go there. That said, I certainly don't think the atom is the smallest indivisible unit of matter - I would say your statement was for the most part wrong.
  8. Sep 14, 2007 #7
    Thanks - Isn't this essentially saying that anything and everything that exists is matter?
  9. Sep 14, 2007 #8
    One consistent thing that I have noticed is that matter (baronic) reflects or emits wavelengths on the Electromagnetic spectrum. That is why we differentiate ordinary matter from dark matter. Matter has mass, obeys newtons laws of motion and on larger scales such as planetoid, planets and galaxies they have a noticeable gravitational attraction with other pieces of matter.
  10. Sep 14, 2007 #9


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    Since when do protons, neutrons, and electrons not have mass or take up space?
  11. Sep 14, 2007 #10


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    Well, Wiki is a good start.
  12. Sep 14, 2007 #11
    Matter - that which possesses mass and geometry, therefore both enacting and obeying the laws of general relativity.
  13. Sep 15, 2007 #12


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    Anyway I guess I can still argue that two electrons can't occupy the same quantum state at the same time and that this is essentially the "quantum version" of the principle of not being in the same "place" at the same time.

    If I'm wrong/ too ambiguous/confused here, please correct me.
  14. Sep 15, 2007 #13


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    I can't help thinking of this little plaque that my dad kept from his McGill days back in the '20s.

    What is matter?
    Never mind.
    What is mind?
    No matter.
  15. Sep 28, 2007 #14
    What is matter : anything that obeys the properties of mass ie creats a gravitational field and obeys the laws of inertia.
  16. Sep 28, 2007 #15


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    This is circular.
  17. Sep 28, 2007 #16
    "Mass grips spacetime, telling it how to curve, but also spacetime itself grips spacetime, transmitting curvature from near to far." John Archibald Wheeler
  18. Sep 29, 2007 #17


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    No, matter and energy are not interchangeable. That famous equation tells you how much energy you get when mass is directly converted to energy. The '=' sign is between numbers not two completely different physical states.
  19. Sep 29, 2007 #18
    Matter is a physical substance that:

    (1) occupies space
    (2) has mass
    (3a) is composed of atoms
    (3b) or is part of an atom (such as quark)
    (4) is convertible to energy

    Matter is a substance and concepts of mass-atoms-quarks-energy are properties of matter.
  20. Sep 29, 2007 #19
    What about this definition: matter is any physical system composed of one or more elementary particles (photons, neutrinos, electrons, protons, neutrons, etc.)?

  21. Oct 1, 2007 #20
    Isn't matter a human sensing approximation of the energy acting at very small scales? Since we observe forces that doesn't let us put an electron just next to another one, we call that volume. Since there are gravitational forces acting appealing this energy we say it has mass which is just a values that describes how much force is there.

    I am a telecommunications engineer. Sorry if this is just a stupid answer. :)
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